When Joe is looking at the building directory, the close-up shows "MORRIS WILLIAM". Yet in the next shot as Joe turns to go to the elevator, it says "MORRIS Wm"
Towards the end, when Joe is receiving a pep talk from his "reflection" in the store glass window, his real reflection briefly appears beside it, thus revealing two reflections; one speaking, the other silent.
The hairstyles, costumes, arrangements, etc. are those fashionable in 1957, not in the Twenties and Thirties, in which the movie is set.
The shot before Frank enters Georgie's office for the 1st time, the boom mic can be seen at the top center of the frame.